<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
      -webkit-tap-highlight-color: transparent;
    }

    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      background: transparent;
      color: #0f172a;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      padding: 12px;
      min-height: 100%;
      user-select: none;
    }

    .chain-container {
      width: 100%;
      max-width: 640px;
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      align-items: center;
      position: relative;
      gap: 4px;
      margin-bottom: 20px;
    }

    /* Connecting arrows SVG layer across the grid */
    .arrows-layer {
      position: absolute;
      top: 32px;
      left: 0;
      width: 100%;
      height: 40px;
      pointer-events: none;
      z-index: 1;
    }

    .node {
      display: flex;
      flex-direction: column;
      align-items: center;
      text-align: center;
      z-index: 2;
      cursor: pointer;
      padding: 6px 2px;
      border-radius: 12px;
      transition: background-color 0.2s ease, transform 0.2s ease;
    }

    .node:active {
      transform: translateY(1px);
    }

    .badge {
      width: 62px;
      height: 62px;
      border-radius: 50%;
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 30px;
      background: #ffffff;
      border: 3px solid #cbd5e1;
      box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05);
      transition: all 0.25s ease;
      position: relative;
    }

    .node.active .badge {
      box-shadow: 0 0 0 4px rgba(34, 183, 255, 0.35), 0 6px 12px rgba(0, 0, 0, 0.1);
    }

    /* Node Color Theming */
    .node[data-step="0"] .badge { border-color: #16a34a; background: #f0fdf4; }
    .node[data-step="1"] .badge { border-color: #d97706; background: #fffbeb; }
    .node[data-step="2"] .badge { border-color: #0284c7; background: #f0f9ff; }
    .node[data-step="3"] .badge { border-color: #475569; background: #f8fafc; }

    .node.active[data-step="0"] .badge { border-color: #15803d; }
    .node.active[data-step="1"] .badge { border-color: #b45309; }
    .node.active[data-step="2"] .badge { border-color: #0369a1; }
    .node.active[data-step="3"] .badge { border-color: #1e293b; }

    .organism-name {
      font-size: 13px;
      font-weight: 700;
      margin-top: 8px;
      color: #0f172a;
      line-height: 1.2;
    }

    .role-pill {
      display: inline-block;
      font-size: 10px;
      font-weight: 600;
      text-transform: uppercase;
      letter-spacing: 0.03em;
      padding: 2px 6px;
      border-radius: 999px;
      margin-top: 4px;
      line-height: 1.2;
    }

    .role-0 { background: #dcfce7; color: #166534; }
    .role-1 { background: #fef3c7; color: #92400e; }
    .role-2 { background: #e0f2fe; color: #075985; }
    .role-3 { background: #f1f5f9; color: #334155; }

    /* Energy Flow Indicator / Info Box */
    .info-panel {
      width: 100%;
      max-width: 580px;
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      border-radius: 12px;
      padding: 10px 14px;
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 12px;
      margin-bottom: 12px;
      min-height: 52px;
    }

    .info-text {
      font-size: 13px;
      color: #334155;
      line-height: 1.3;
      font-weight: 500;
    }

    .info-text strong {
      color: #0f172a;
    }

    .step-nav {
      display: flex;
      gap: 4px;
    }

    .nav-btn {
      background: #ffffff;
      border: 1px solid #cbd5e1;
      border-radius: 6px;
      font-size: 12px;
      font-weight: 600;
      color: #334155;
      padding: 4px 8px;
      cursor: pointer;
      display: flex;
      align-items: center;
      justify-content: center;
    }

    .nav-btn:hover {
      background: #f1f5f9;
      border-color: #94a3b8;
    }

    /* Core Law Rule Pill */
    .rule-pill {
      display: flex;
      align-items: center;
      gap: 6px;
      background: #eff6ff;
      border: 1px solid #bfdbfe;
      color: #1e40af;
      font-size: 11.5px;
      font-weight: 600;
      padding: 6px 12px;
      border-radius: 20px;
      text-align: center;
    }

    /* Animated Flow Dots */
    @keyframes flowAnim {
      0% { stroke-dashoffset: 24; }
      100% { stroke-dashoffset: 0; }
    }

    .flow-line {
      stroke: #38bdf8;
      stroke-width: 3.5;
      stroke-linecap: round;
      stroke-dasharray: 6 6;
      animation: flowAnim 1.2s linear infinite;
    }

    .flow-arrowhead {
      fill: #0284c7;
    }

    .arrow-subtext {
      font-size: 8px;
      font-weight: 700;
      fill: #64748b;
      letter-spacing: 0.02em;
    }

    @media (max-width: 440px) {
      .badge {
        width: 50px;
        height: 50px;
        font-size: 24px;
      }
      .organism-name {
        font-size: 11px;
      }
      .role-pill {
        font-size: 8.5px;
        padding: 2px 4px;
      }
      .arrows-layer {
        top: 26px;
      }
      .info-text {
        font-size: 12px;
      }
      .rule-pill {
        font-size: 10px;
        padding: 4px 8px;
      }
    }
  </style>
</head>
<body>

  
  <div class="chain-container">
    
    
    <svg class="arrows-layer" viewBox="0 0 600 40" preserveAspectRatio="none">
      <defs>
        <marker id="arrow1" viewBox="0 0 8 8" refX="6" refY="4" markerWidth="6" markerHeight="6" orient="auto-start-reverse">
          <polygon points="0 1, 8 4, 0 7" class="flow-arrowhead" />
        </marker>
        <marker id="arrow2" viewBox="0 0 8 8" refX="6" refY="4" markerWidth="6" markerHeight="6" orient="auto-start-reverse">
          <polygon points="0 1, 8 4, 0 7" class="flow-arrowhead" />
        </marker>
        <marker id="arrow3" viewBox="0 0 8 8" refX="6" refY="4" markerWidth="6" markerHeight="6" orient="auto-start-reverse">
          <polygon points="0 1, 8 4, 0 7" class="flow-arrowhead" />
        </marker>
      </defs>

      
      <g>
        <line x1="105" y1="18" x2="165" y2="18" stroke="#cbd5e1" stroke-width="2.5" />
        <line x1="105" y1="18" x2="165" y2="18" class="flow-line" marker-end="url(#arrow1)" />
        <text x="135" y="32" text-anchor="middle" class="arrow-subtext">ENERGY →</text>
      </g>

      
      <g>
        <line x1="255" y1="18" x2="315" y2="18" stroke="#cbd5e1" stroke-width="2.5" />
        <line x1="255" y1="18" x2="315" y2="18" class="flow-line" marker-end="url(#arrow2)" />
        <text x="285" y="32" text-anchor="middle" class="arrow-subtext">ENERGY →</text>
      </g>

      
      <g>
        <line x1="405" y1="18" x2="465" y2="18" stroke="#cbd5e1" stroke-width="2.5" />
        <line x1="405" y1="18" x2="465" y2="18" class="flow-line" marker-end="url(#arrow3)" />
        <text x="435" y="32" text-anchor="middle" class="arrow-subtext">ENERGY →</text>
      </g>
    </svg>

    
    <div class="node active" data-step="0" onclick="selectNode(0)">
      <div class="badge">🍃</div>
      <div class="organism-name">Oak Leaf</div>
      <div class="role-pill role-0">Producer</div>
    </div>

    
    <div class="node" data-step="1" onclick="selectNode(1)">
      <div class="badge">🐛</div>
      <div class="organism-name">Caterpillar</div>
      <div class="role-pill role-1">Herbivore</div>
    </div>

    
    <div class="node" data-step="2" onclick="selectNode(2)">
      <div class="badge">🐦</div>
      <div class="organism-name">Blue Tit</div>
      <div class="role-pill role-2">Predator</div>
    </div>

    
    <div class="node" data-step="3" onclick="selectNode(3)">
      <div class="badge">🦅</div>
      <div class="organism-name">Sparrowhawk</div>
      <div class="role-pill role-3">Apex</div>
    </div>

  </div>

  
  <div class="info-panel">
    <div class="info-text" id="infoText">
      <strong>Oak Leaf:</strong> Traps sunlight via photosynthesis to make food.
    </div>
    <div class="step-nav">
      <button class="nav-btn" onclick="prevStep()">◀</button>
      <button class="nav-btn" onclick="nextStep()">▶</button>
    </div>
  </div>

  
  <div class="rule-pill">
    <span>💡</span>
    <span><strong>Rule:</strong> Arrows point in direction of energy transfer (food → eater).</span>
  </div>

  <script>
    const facts = [
      "<strong>Oak Leaf (Producer):</strong> Captures solar energy through photosynthesis.",
      "<strong>Caterpillar (Primary Consumer):</strong> Eats leaves to obtain stored plant energy.",
      "<strong>Blue Tit (Secondary Consumer):</strong> Hunts caterpillars, transferring energy up.",
      "<strong>Sparrowhawk (Apex Predator):</strong> Top carnivore; preys on small woodland birds."
    ];

    let currentStep = 0;
    const nodes = document.querySelectorAll('.node');
    const infoEl = document.getElementById('infoText');

    function selectNode(index) {
      currentStep = index;
      nodes.forEach((n, i) => {
        n.classList.toggle('active', i === index);
      });
      infoEl.innerHTML = facts[index];
    }

    function nextStep() {
      selectNode((currentStep + 1) % nodes.length);
    }

    function prevStep() {
      selectNode((currentStep - 1 + nodes.length) % nodes.length);
    }
  </script>
</body>
</html>

British Woodland Food Chains

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }

    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      color: #1e2945;
      background: transparent;
      padding: 12px;
      display: flex;
      flex-direction: column;
      justify-content: center;
      min-height: 100%;
    }

    .comparison-grid {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
      gap: 16px;
      width: 100%;
      max-width: 640px;
      margin: 0 auto;
    }

    .card-panel {
      background: #ffffff;
      border-radius: 16px;
      padding: 16px;
      display: flex;
      flex-direction: column;
      align-items: center;
      text-align: center;
      position: relative;
    }

    .card-panel.correct {
      border: 2px solid #86efac;
      background: linear-gradient(180deg, #f0fdf4 0%, #ffffff 100%);
    }

    .card-panel.incorrect {
      border: 2px solid #fca5a5;
      background: linear-gradient(180deg, #fef2f2 0%, #ffffff 100%);
    }

    .badge {
      display: inline-flex;
      align-items: center;
      gap: 6px;
      font-size: 13px;
      font-weight: 800;
      letter-spacing: 0.5px;
      text-transform: uppercase;
      padding: 4px 12px;
      border-radius: 20px;
      margin-bottom: 12px;
    }

    .badge.correct {
      background: #22c55e;
      color: #ffffff;
    }

    .badge.incorrect {
      background: #ef4444;
      color: #ffffff;
    }

    .chain-flow {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      width: 100%;
      margin: 12px 0;
    }

    .item {
      display: flex;
      flex-direction: column;
      align-items: center;
      width: 72px;
    }

    .item-icon {
      font-size: 34px;
      line-height: 1;
      filter: drop-shadow(0 2px 4px rgba(0,0,0,0.08));
    }

    .item-name {
      font-size: 12px;
      font-weight: 700;
      color: #334155;
      margin-top: 6px;
    }

    .arrow-container {
      flex: 1;
      display: flex;
      flex-direction: column;
      align-items: center;
      position: relative;
      min-width: 60px;
      max-width: 90px;
    }

    .arrow-label {
      font-size: 10px;
      font-weight: 700;
      letter-spacing: 0.5px;
      text-transform: uppercase;
      margin-bottom: 4px;
    }

    .correct .arrow-label {
      color: #16a34a;
    }

    .incorrect .arrow-label {
      color: #dc2626;
    }

    .arrow-svg {
      width: 100%;
      height: 28px;
      overflow: visible;
    }

    .caption {
      font-size: 13px;
      font-weight: 600;
      line-height: 1.35;
      margin-top: 8px;
    }

    .correct .caption {
      color: #15803d;
    }

    .incorrect .caption {
      color: #b91c1c;
    }

    /* Animated energy particle */
    @keyframes pulse-energy {
      0% {
        offset-distance: 0%;
        opacity: 0;
      }
      20% {
        opacity: 1;
      }
      80% {
        opacity: 1;
      }
      100% {
        offset-distance: 100%;
        opacity: 0;
      }
    }

    .energy-dot {
      animation: moveDot 2s ease-in-out infinite;
    }

    @keyframes moveDot {
      0% {
        cx: 10;
        opacity: 0;
      }
      25% {
        opacity: 1;
      }
      75% {
        opacity: 1;
      }
      100% {
        cx: 65;
        opacity: 0;
      }
    }
  </style>
</head>
<body>

  <div class="comparison-grid">
    
    <div class="card-panel correct">
      <div class="badge correct">✓ Correct</div>

      <div class="chain-flow">
        <div class="item">
          <div class="item-icon">🍃</div>
          <div class="item-name">Oak Leaf</div>
        </div>

        <div class="arrow-container">
          <span class="arrow-label">Energy</span>
          <svg class="arrow-svg" viewBox="0 0 75 24">
            <defs>
              <marker id="arrow-green" viewBox="0 0 10 10" refX="6" refY="5" markerWidth="6" markerHeight="6" orient="auto-start-reverse">
                <path d="M 0 1.5 L 8 5 L 0 8.5 z" fill="#16a34a" />
              </marker>
            </defs>
            
            <line x1="5" y1="12" x2="65" y2="12" stroke="#16a34a" stroke-width="4" stroke-linecap="round" marker-end="url(#arrow-green)" />
            
            <circle class="energy-dot" cy="12" r="3.5" fill="#facc15" />
          </svg>
        </div>

        <div class="item">
          <div class="item-icon">🐛</div>
          <div class="item-name">Caterpillar</div>
        </div>
      </div>

      <div class="caption">
        Energy moves from leaf into caterpillar
      </div>
    </div>

    
    <div class="card-panel incorrect">
      <div class="badge incorrect">✗ Common Mistake</div>

      <div class="chain-flow">
        <div class="item">
          <div class="item-icon">🐛</div>
          <div class="item-name">Caterpillar</div>
        </div>

        <div class="arrow-container">
          <span class="arrow-label">Attacks?</span>
          <svg class="arrow-svg" viewBox="0 0 75 24">
            <defs>
              <marker id="arrow-red" viewBox="0 0 10 10" refX="6" refY="5" markerWidth="6" markerHeight="6" orient="auto-start-reverse">
                <path d="M 0 1.5 L 8 5 L 0 8.5 z" fill="#dc2626" />
              </marker>
            </defs>
            
            <line x1="5" y1="12" x2="65" y2="12" stroke="#dc2626" stroke-width="3" stroke-dasharray="4 3" stroke-linecap="round" marker-end="url(#arrow-red)" />
            
            <path d="M 32 6 L 44 18 M 44 6 L 32 18" stroke="#dc2626" stroke-width="3" stroke-linecap="round" />
          </svg>
        </div>

        <div class="item">
          <div class="item-icon">🍃</div>
          <div class="item-name">Oak Leaf</div>
        </div>
      </div>

      <div class="caption">
        Mistake: arrows do NOT mean who hunts who!
      </div>
    </div>
  </div>

</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }

    body {
      font-family: system-ui, -apple-system, sans-serif;
      background: #f8fafc;
      color: #1e2945;
      min-height: 100%;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      padding: 12px 8px;
      user-select: none;
    }

    .controls {
      display: flex;
      gap: 8px;
      margin-bottom: 12px;
      flex-wrap: wrap;
      justify-content: center;
    }

    .toggle-btn {
      appearance: none;
      border: 1.5px solid #cbd5e1;
      background: #ffffff;
      padding: 6px 12px;
      border-radius: 999px;
      font-size: 13px;
      font-weight: 600;
      color: #475569;
      cursor: pointer;
      display: flex;
      align-items: center;
      gap: 6px;
      transition: background 0.2s, border-color 0.2s, color 0.2s, box-shadow 0.2s;
    }

    .toggle-btn.active {
      background: #0284c7;
      border-color: #0284c7;
      color: #ffffff;
      box-shadow: 0 2px 8px rgba(2, 132, 199, 0.3);
    }

    .chain-container {
      position: relative;
      width: 100%;
      max-width: 580px;
      display: grid;
      grid-template-columns: 1fr 18px 1fr 18px 1fr 22px 1.15fr;
      align-items: center;
      gap: 2px;
    }

    .node {
      background: #ffffff;
      border: 1.5px solid #e2e8f0;
      border-radius: 12px;
      padding: 8px 4px;
      display: flex;
      flex-direction: column;
      align-items: center;
      text-align: center;
      position: relative;
      transition: border-color 0.3s, box-shadow 0.3s, background 0.3s;
    }

    .node.active-path {
      border-color: #f59e0b;
      box-shadow: 0 0 0 2px rgba(245, 158, 11, 0.25), 0 4px 10px rgba(245, 158, 11, 0.15);
      background: #fffbeb;
    }

    .node-icon {
      font-size: 26px;
      line-height: 1.1;
      margin-bottom: 2px;
    }

    .node-name {
      font-size: 12px;
      font-weight: 700;
      color: #0f172a;
      line-height: 1.2;
    }

    .node-tag {
      font-size: 10px;
      font-weight: 600;
      color: #64748b;
      margin-top: 2px;
      text-transform: uppercase;
      letter-spacing: 0.3px;
    }

    .node.active-path .node-tag {
      color: #b45309;
    }

    .arrow-col {
      display: flex;
      align-items: center;
      justify-content: center;
      color: #94a3b8;
      font-size: 14px;
      font-weight: 900;
      transition: color 0.3s;
    }

    .arrow-col.active {
      color: #f59e0b;
    }

    .branch-col {
      display: flex;
      flex-direction: column;
      gap: 10px;
    }

    .branch-node {
      cursor: pointer;
      padding: 6px 4px;
      opacity: 0.45;
      transition: opacity 0.3s, border-color 0.3s, box-shadow 0.3s, background 0.3s;
    }

    .branch-node.active-path {
      opacity: 1;
    }

    .fork-svg {
      width: 22px;
      height: 120px;
    }

    .fork-path {
      fill: none;
      stroke: #cbd5e1;
      stroke-width: 2.5;
      stroke-linecap: round;
      stroke-linejoin: round;
      transition: stroke 0.3s;
    }

    .fork-path.active {
      stroke: #f59e0b;
    }

    /* Energy pulse dot */
    .energy-tracker {
      position: absolute;
      width: 10px;
      height: 10px;
      background: #f59e0b;
      border-radius: 50%;
      box-shadow: 0 0 8px 2px #f59e0b;
      pointer-events: none;
      opacity: 0;
      z-index: 10;
    }

    .energy-bar {
      margin-top: 14px;
      display: inline-flex;
      align-items: center;
      gap: 6px;
      font-size: 11px;
      font-weight: 700;
      color: #d97706;
      background: #fef3c7;
      padding: 4px 10px;
      border-radius: 999px;
    }

    .energy-spark {
      animation: pulse 1.2s infinite ease-in-out;
    }

    @keyframes pulse {
      0%, 100% { opacity: 0.4; transform: scale(0.9); }
      50% { opacity: 1; transform: scale(1.2); }
    }
  </style>
</head>
<body>

  <div class="controls">
    <button id="btnSky" class="toggle-btn active" onclick="setPredator('sky')">
      🦅 Sky Predator
    </button>
    <button id="btnGround" class="toggle-btn" onclick="setPredator('ground')">
      🦊 Ground Predator
    </button>
  </div>

  <div class="chain-container" id="chainBox">
    
    <div class="node active-path" id="nodeLeaf">
      <div class="node-icon">🍃</div>
      <div class="node-name">Oak Leaf</div>
      <div class="node-tag">Producer</div>
    </div>

    
    <div class="arrow-col active" id="arr1">➔</div>

    
    <div class="node active-path" id="nodeCat">
      <div class="node-icon">🐛</div>
      <div class="node-name">Caterpillar</div>
      <div class="node-tag">Herbivore</div>
    </div>

    
    <div class="arrow-col active" id="arr2">➔</div>

    
    <div class="node active-path" id="nodeBird">
      <div class="node-icon">🐦</div>
      <div class="node-name">Blue Tit</div>
      <div class="node-tag">Carnivore</div>
    </div>

    
    <div class="arrow-col">
      <svg class="fork-svg" viewBox="0 0 22 120">
        <path id="pathTop" class="fork-path active" d="M 0 60 C 12 60, 10 24, 22 24" />
        <path id="pathBtm" class="fork-path" d="M 0 60 C 12 60, 10 96, 22 96" />
      </svg>
    </div>

    
    <div class="branch-col">
      <div class="node branch-node active-path" id="nodeHawk" onclick="setPredator('sky')">
        <div class="node-icon">🦅</div>
        <div class="node-name">Sparrowhawk</div>
        <div class="node-tag">Apex</div>
      </div>
      <div class="node branch-node" id="nodeFox" onclick="setPredator('ground')">
        <div class="node-icon">🦊</div>
        <div class="node-name">Fox</div>
        <div class="node-tag">Apex</div>
      </div>
    </div>
  </div>

  <div class="energy-bar">
    <span class="energy-spark">⚡</span> Energy Flow
  </div>

  <script>
    let currentPredator = 'sky';

    function setPredator(type) {
      currentPredator = type;
      const isSky = type === 'sky';

      // Buttons
      document.getElementById('btnSky').classList.toggle('active', isSky);
      document.getElementById('btnGround').classList.toggle('active', !isSky);

      // Predators
      document.getElementById('nodeHawk').classList.toggle('active-path', isSky);
      document.getElementById('nodeFox').classList.toggle('active-path', !isSky);

      // SVG branches
      document.getElementById('pathTop').classList.toggle('active', isSky);
      document.getElementById('pathBtm').classList.toggle('active', !isSky);

      triggerPulse();
    }

    function triggerPulse() {
      const nodes = [
        document.getElementById('nodeLeaf'),
        document.getElementById('nodeCat'),
        document.getElementById('nodeBird'),
        currentPredator === 'sky' ? document.getElementById('nodeHawk') : document.getElementById('nodeFox')
      ];

      nodes.forEach((node, i) => {
        setTimeout(() => {
          node.style.transition = 'transform 0.18s ease, background 0.18s';
          node.style.transform = 'scale(1.05)';
          node.style.background = '#fef08a';
          setTimeout(() => {
            node.style.transform = 'scale(1)';
            node.style.background = '#fffbeb';
          }, 240);
        }, i * 200);
      });
    }

    // Auto-pulse on load
    triggerPulse();
  </script>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }

    body {
      width: 100%;
      height: 100%;
      background: #f0fdf4;
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      padding: 12px;
      user-select: none;
      overflow: hidden;
    }

    .diagram-view {
      position: relative;
      width: 100%;
      max-width: 520px;
      flex: 1;
      display: flex;
      align-items: center;
      justify-content: center;
    }

    svg {
      width: 100%;
      height: 100%;
      max-height: 380px;
      overflow: visible;
    }

    /* Soft pulsing sun */
    .sun-glow {
      animation: pulseSun 3s ease-in-out infinite;
      transform-origin: 90px 75px;
    }

    @keyframes pulseSun {
      0%, 100% { transform: scale(1); opacity: 0.85; }
      50% { transform: scale(1.08); opacity: 1; }
    }

    /* Beaming sunlight rays */
    .sunbeam {
      opacity: 0.45;
      animation: beamShimmer 4s ease-in-out infinite alternate;
    }

    .beam-2 { animation-delay: 1.5s; }
    .beam-3 { animation-delay: 0.8s; }

    @keyframes beamShimmer {
      0% { opacity: 0.3; }
      100% { opacity: 0.6; }
    }

    /* Glowing energy sparkles flowing from sun to canopy */
    .sparkle {
      fill: #fef08a;
      filter: drop-shadow(0 0 4px #eab308);
      animation: streamEnergy 3s ease-in infinite;
      opacity: 0;
    }

    .sp-1 { animation-delay: 0s; }
    .sp-2 { animation-delay: 0.7s; }
    .sp-3 { animation-delay: 1.4s; }
    .sp-4 { animation-delay: 2.1s; }
    .sp-5 { animation-delay: 1.0s; }

    @keyframes streamEnergy {
      0% {
        transform: translate(0, 0) scale(0.6);
        opacity: 0;
      }
      20% {
        opacity: 1;
      }
      80% {
        opacity: 1;
      }
      100% {
        transform: translate(160px, 150px) scale(1.2);
        opacity: 0;
      }
    }

    /* Canopy leaf sparkles */
    .canopy-sparkle {
      animation: sparkleGaze 2.5s ease-in-out infinite alternate;
      transform-origin: center;
    }

    .cs-2 { animation-delay: 0.9s; }
    .cs-3 { animation-delay: 1.7s; }

    @keyframes sparkleGaze {
      0% { opacity: 0.2; transform: scale(0.7); }
      100% { opacity: 1; transform: scale(1.25); }
    }

    /* Badge styling */
    .info-badge {
      background: #ffffff;
      border: 1.5px solid #86efac;
      border-radius: 9999px;
      padding: 8px 18px;
      display: flex;
      align-items: center;
      gap: 8px;
      box-shadow: 0 2px 8px rgba(21, 128, 61, 0.08);
      font-size: 14px;
      font-weight: 600;
      color: #15803d;
      text-align: center;
      margin-top: 4px;
    }

    .producer-tag {
      background: #dcfce7;
      color: #166534;
      padding: 2px 8px;
      border-radius: 9999px;
      font-size: 12px;
      font-weight: 700;
      text-transform: uppercase;
      letter-spacing: 0.04em;
    }

    .label-text {
      font-size: 13px;
      font-weight: 700;
      fill: #166534;
    }

    .sun-text {
      font-size: 13px;
      font-weight: 700;
      fill: #854d0e;
    }
  </style>
</head>
<body>

  <div class="diagram-view">
    <svg viewBox="0 0 460 330" aria-label="Oak tree making energy from sunlight">
      <defs>
        
        <linearGradient id="beamGrad" x1="0%" y1="0%" x2="80%" y2="100%">
          <stop offset="0%" stop-color="#fef08a" stop-opacity="0.85" />
          <stop offset="60%" stop-color="#fef9c3" stop-opacity="0.35" />
          <stop offset="100%" stop-color="#dcfce7" stop-opacity="0.0" />
        </linearGradient>
        
        
        <linearGradient id="canopyGrad" x1="0%" y1="0%" x2="0%" y2="100%">
          <stop offset="0%" stop-color="#4ade80" />
          <stop offset="100%" stop-color="#16a34a" />
        </linearGradient>

        
        <linearGradient id="trunkGrad" x1="0%" y1="0%" x2="100%" y2="0%">
          <stop offset="0%" stop-color="#78350f" />
          <stop offset="50%" stop-color="#92400e" />
          <stop offset="100%" stop-color="#5c2608" />
        </linearGradient>
      </defs>

      
      <path d="M 0 310 Q 150 280 290 290 T 460 305 L 460 330 L 0 330 Z" fill="#bbf7d0" />
      <path d="M 0 320 Q 230 295 460 315 L 460 330 L 0 330 Z" fill="#86efac" opacity="0.6" />

      
      <polygon class="sunbeam" points="90,75 220,180 180,240" fill="url(#beamGrad)" />
      <polygon class="sunbeam beam-2" points="90,75 320,130 250,220" fill="url(#beamGrad)" />
      <polygon class="sunbeam beam-3" points="90,75 380,180 320,240" fill="url(#beamGrad)" />

      
      
      <path d="M 270 300 C 265 240 260 210 270 170 C 280 210 295 240 310 300 C 325 306 335 312 340 315 C 320 310 305 305 290 302 C 280 304 265 312 250 315 C 258 310 265 304 270 300 Z" fill="url(#trunkGrad)" />
      
      <path d="M 270 180 Q 240 140 210 130 Q 240 145 265 190 Z" fill="#78350f" />
      <path d="M 275 175 Q 315 135 345 130 Q 315 145 280 185 Z" fill="#78350f" />

      
      
      <ellipse cx="280" cy="165" rx="100" ry="75" fill="#15803d" />
      
      
      <circle cx="210" cy="170" r="50" fill="#16a34a" />
      <circle cx="345" cy="170" r="50" fill="#16a34a" />
      <circle cx="240" cy="125" r="55" fill="url(#canopyGrad)" />
      <circle cx="315" cy="125" r="55" fill="url(#canopyGrad)" />
      <circle cx="280" cy="95" r="52" fill="#4ade80" />
      
      
      <circle cx="275" cy="140" r="48" fill="#22c55e" />
      <ellipse cx="250" cy="100" rx="30" ry="22" fill="#86efac" opacity="0.6" />

      
      <g>
        <circle class="sparkle sp-1" cx="115" cy="90" r="5" />
        <path class="sparkle sp-1" d="M 115 82 Q 115 90 123 90 Q 115 90 115 98 Q 115 90 107 90 Z" />

        <circle class="sparkle sp-2" cx="135" cy="105" r="4" />
        <circle class="sparkle sp-5" cx="150" cy="85" r="6" />
        <path class="sparkle sp-3" d="M 160 120 Q 160 128 168 128 Q 160 128 160 136 Q 160 128 152 128 Z" />

        <circle class="sparkle sp-4" cx="180" cy="140" r="5.5" />
      </g>

      
      <g>
        <path class="canopy-sparkle cs-1" d="M 235 125 Q 235 133 243 133 Q 235 133 235 141 Q 235 133 227 133 Z" fill="#fef08a" />
        <path class="canopy-sparkle cs-2" d="M 315 110 Q 315 118 323 118 Q 315 118 315 126 Q 315 118 307 118 Z" fill="#fef08a" />
        <path class="canopy-sparkle cs-3" d="M 275 80 Q 275 88 283 88 Q 275 88 275 96 Q 275 88 267 88 Z" fill="#fef08a" />
        <path class="canopy-sparkle cs-2" d="M 290 155 Q 290 162 297 162 Q 290 162 290 169 Q 290 162 283 162 Z" fill="#fef08a" />
      </g>

      
      <g class="sun-glow">
        <circle cx="90" cy="75" r="42" fill="#fef08a" opacity="0.45" />
        <circle cx="90" cy="75" r="32" fill="#fde047" />
        <circle cx="90" cy="75" r="25" fill="#f59e0b" />
        
        <g stroke="#f59e0b" stroke-width="3" stroke-linecap="round">
          <line x1="90" y1="36" x2="90" y2="28" />
          <line x1="90" y1="114" x2="90" y2="122" />
          <line x1="51" y1="75" x2="43" y2="75" />
          <line x1="129" y1="75" x2="137" y2="75" />
          <line x1="62" y1="47" x2="56" y2="41" />
          <line x1="118" y1="103" x2="124" y2="109" />
          <line x1="62" y1="103" x2="56" y2="109" />
          <line x1="118" y1="47" x2="124" y2="41" />
        </g>
      </g>

      
      <text x="90" y="145" text-anchor="middle" class="sun-text">Sunlight ☀️</text>
      <text x="280" y="55" text-anchor="middle" class="label-text">Oak Canopy 🍃</text>
    </svg>
  </div>

  
  <div class="info-badge">
    <span class="producer-tag">Producer</span>
    <span>Oak Tree (Makes energy from sunlight)</span>
  </div>

</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      -webkit-tap-highlight-color: transparent;
    }

    body {
      background: #ffffff;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      min-height: 100%;
      padding: 16px 8px;
    }

    .controls {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 6px;
      flex-wrap: wrap;
      margin-bottom: 12px;
    }

    .step-btn {
      background: #f1f5f9;
      border: 1px solid #cbd5e1;
      border-radius: 20px;
      padding: 6px 12px;
      font-size: 13px;
      font-weight: 600;
      color: #475569;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      gap: 4px;
      transition: all 0.25s ease;
    }

    .step-btn.active {
      background: #ef4444;
      border-color: #dc2626;
      color: #ffffff;
      box-shadow: 0 2px 6px rgba(239, 68, 68, 0.35);
    }

    .play-btn {
      background: #2563eb;
      border: 1px solid #1d4ed8;
      border-radius: 20px;
      padding: 6px 14px;
      font-size: 13px;
      font-weight: 600;
      color: #ffffff;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      gap: 4px;
      transition: all 0.2s ease;
    }

    .chain-container {
      width: 100%;
      max-width: 620px;
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 8px;
      position: relative;
      margin: auto 0;
    }

    .node {
      display: flex;
      flex-direction: column;
      align-items: center;
      text-align: center;
      position: relative;
      background: #f8fafc;
      border: 1.5px solid #e2e8f0;
      border-radius: 14px;
      padding: 12px 4px 10px;
      transition: border-color 0.3s ease, background-color 0.3s ease, transform 0.3s ease;
    }

    .node.healthy {
      border-color: #22c55e;
      background: #f0fdf4;
    }

    .node.collapsed {
      border-color: #ef4444;
      background: #fef2f2;
    }

    .icon-box {
      width: 52px;
      height: 52px;
      border-radius: 50%;
      background: #ffffff;
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 28px;
      margin-bottom: 6px;
      position: relative;
      box-shadow: 0 2px 5px rgba(0,0,0,0.06);
      transition: transform 0.3s ease, filter 0.3s ease;
    }

    .collapsed .icon-box {
      filter: grayscale(80%) opacity(0.7);
      transform: translateY(3px);
    }

    .node-name {
      font-size: 13px;
      font-weight: 700;
      color: #1e2945;
      margin-bottom: 2px;
    }

    .trophic-label {
      font-size: 11px;
      font-weight: 500;
      color: #64748b;
      margin-bottom: 6px;
    }

    .status-badge {
      font-size: 11px;
      font-weight: 700;
      line-height: 1.2;
      padding: 4px 6px;
      border-radius: 6px;
      width: 92%;
      min-height: 38px;
      display: flex;
      align-items: center;
      justify-content: center;
      background: #ecfdf5;
      color: #059669;
      border: 1px solid #a7f3d0;
      transition: all 0.3s ease;
    }

    .collapsed .status-badge {
      background: #fee2e2;
      color: #dc2626;
      border-color: #fca5a5;
    }

    .badge-icon {
      font-size: 13px;
      margin-right: 3px;
      display: inline-block;
    }

    /* Flow connector arrows */
    .arrow-divider {
      position: absolute;
      top: 36px;
      right: -9px;
      width: 16px;
      height: 16px;
      background: #ffffff;
      border: 1px solid #cbd5e1;
      border-radius: 50%;
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 10px;
      color: #64748b;
      z-index: 2;
    }

    .node:last-child .arrow-divider {
      display: none;
    }

    .banner {
      font-size: 13px;
      font-weight: 600;
      color: #475569;
      text-align: center;
      background: #f8fafc;
      border-radius: 8px;
      padding: 6px 14px;
      margin-top: 8px;
    }

    @media (max-width: 480px) {
      .chain-container {
        grid-template-columns: repeat(2, 1fr);
        row-gap: 12px;
      }
      .node:nth-child(2) .arrow-divider {
        display: none;
      }
      .icon-box {
        width: 44px;
        height: 44px;
        font-size: 24px;
      }
    }
  </style>
</head>
<body>

  
  <div class="controls">
    <button class="step-btn" onclick="setStep(0)">Healthy</button>
    <button class="step-btn" onclick="setStep(1)">1. Drought</button>
    <button class="step-btn" onclick="setStep(2)">2. Herbivore</button>
    <button class="step-btn" onclick="setStep(3)">3. Bird</button>
    <button class="step-btn" onclick="setStep(4)">4. Predator</button>
    <button id="playBtn" class="play-btn" onclick="togglePlay()">⏸ Pause</button>
  </div>

  
  <div class="chain-container">
    
    
    <div id="node-0" class="node healthy">
      <div class="arrow-divider">→</div>
      <div class="icon-box">🌾</div>
      <div class="node-name">Grass</div>
      <div class="trophic-label">Producer</div>
      <div id="badge-0" class="status-badge">
        <span class="badge-icon">✓</span> Alive
      </div>
    </div>

    
    <div id="node-1" class="node healthy">
      <div class="arrow-divider">→</div>
      <div class="icon-box">🦗</div>
      <div class="node-name">Grasshopper</div>
      <div class="trophic-label">Primary</div>
      <div id="badge-1" class="status-badge">
        <span class="badge-icon">✓</span> Stable
      </div>
    </div>

    
    <div id="node-2" class="node healthy">
      <div class="arrow-divider">→</div>
      <div class="icon-box">🐦</div>
      <div class="node-name">Meadowlark</div>
      <div class="trophic-label">Secondary</div>
      <div id="badge-2" class="status-badge">
        <span class="badge-icon">✓</span> Stable
      </div>
    </div>

    
    <div id="node-3" class="node healthy">
      <div class="icon-box">🦅</div>
      <div class="node-name">Hawk</div>
      <div class="trophic-label">Top Predator</div>
      <div id="badge-3" class="status-badge">
        <span class="badge-icon">✓</span> Stable
      </div>
    </div>

  </div>

  
  <div id="infoBanner" class="banner">
    Healthy Meadow Ecosystem
  </div>

  <script>
    let currentStep = 0;
    let isPlaying = true;
    let timer = null;

    const stages = [
      {
        banner: "Healthy Meadow Ecosystem",
        collapsed: [false, false, false, false],
        badges: [
          '<span class="badge-icon">✓</span> Alive',
          '<span class="badge-icon">✓</span> Stable',
          '<span class="badge-icon">✓</span> Stable',
          '<span class="badge-icon">✓</span> Stable'
        ]
      },
      {
        banner: "Step 1: Producer dies from drought",
        collapsed: [true, false, false, false],
        badges: [
          '<span class="badge-icon">✕</span> Drought',
          '<span class="badge-icon">✓</span> Stable',
          '<span class="badge-icon">✓</span> Stable',
          '<span class="badge-icon">✓</span> Stable'
        ]
      },
      {
        banner: "Step 2: Herbivores run out of food",
        collapsed: [true, true, false, false],
        badges: [
          '<span class="badge-icon">✕</span> Drought',
          '<span class="badge-icon">↓</span> No Food',
          '<span class="badge-icon">✓</span> Stable',
          '<span class="badge-icon">✓</span> Stable'
        ]
      },
      {
        banner: "Step 3: Insect-eaters starve or leave",
        collapsed: [true, true, true, false],
        badges: [
          '<span class="badge-icon">✕</span> Drought',
          '<span class="badge-icon">↓</span> No Food',
          '<span class="badge-icon">↓</span> Starves',
          '<span class="badge-icon">✓</span> Stable'
        ]
      },
      {
        banner: "Step 4: Top predators crash",
        collapsed: [true, true, true, true],
        badges: [
          '<span class="badge-icon">✕</span> Drought',
          '<span class="badge-icon">↓</span> No Food',
          '<span class="badge-icon">↓</span> Starves',
          '<span class="badge-icon">↓</span> Crashes'
        ]
      }
    ];

    function updateView() {
      const stage = stages[currentStep];

      // Update nodes
      for (let i = 0; i < 4; i++) {
        const node = document.getElementById('node-' + i);
        const badge = document.getElementById('badge-' + i);

        if (stage.collapsed[i]) {
          node.classList.remove('healthy');
          node.classList.add('collapsed');
        } else {
          node.classList.remove('collapsed');
          node.classList.add('healthy');
        }
        badge.innerHTML = stage.badges[i];
      }

      // Update banner
      document.getElementById('infoBanner').textContent = stage.banner;

      // Update buttons
      const buttons = document.querySelectorAll('.step-btn');
      buttons.forEach((btn, index) => {
        if (index === currentStep) {
          btn.classList.add('active');
        } else {
          btn.classList.remove('active');
        }
      });
    }

    function setStep(idx) {
      currentStep = idx;
      updateView();
    }

    function nextStep() {
      currentStep = (currentStep + 1) % stages.length;
      updateView();
    }

    function startAutoPlay() {
      stopAutoPlay();
      timer = setInterval(nextStep, 3200);
    }

    function stopAutoPlay() {
      if (timer) {
        clearInterval(timer);
        timer = null;
      }
    }

    function togglePlay() {
      isPlaying = !isPlaying;
      const playBtn = document.getElementById('playBtn');
      if (isPlaying) {
        playBtn.innerHTML = '⏸ Pause';
        startAutoPlay();
      } else {
        playBtn.innerHTML = '▶ Play';
        stopAutoPlay();
      }
    }

    // Initialize
    updateView();
    startAutoPlay();
  </script>
</body>
</html>

What Happens When a Producer Disappears?

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }
    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
      background: transparent;
      color: #1e2945;
      padding: 10px;
      display: flex;
      flex-direction: column;
      justify-content: center;
      min-height: 100%;
    }
    .comparison-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 12px;
      width: 100%;
      max-width: 600px;
      margin: 0 auto;
    }
    @media (max-width: 440px) {
      .comparison-grid {
        grid-template-columns: 1fr;
        gap: 10px;
      }
    }
    .impact-card {
      background: #ffffff;
      border: 2px solid #e2e8f0;
      border-radius: 14px;
      padding: 14px 12px;
      display: flex;
      flex-direction: column;
      align-items: center;
      text-align: center;
      box-shadow: 0 3px 10px rgba(0, 0, 0, 0.04);
      cursor: pointer;
      user-select: none;
      transition: border-color 0.25s ease, box-shadow 0.25s ease;
    }
    .impact-card.active-direct {
      border-color: #f97316;
      box-shadow: 0 4px 16px rgba(249, 115, 22, 0.18);
    }
    .impact-card.active-indirect {
      border-color: #8b5cf6;
      box-shadow: 0 4px 16px rgba(139, 92, 246, 0.18);
    }
    .badge {
      font-size: 13px;
      font-weight: 800;
      letter-spacing: 0.05em;
      text-transform: uppercase;
      padding: 4px 10px;
      border-radius: 20px;
      margin-bottom: 12px;
      display: inline-block;
    }
    .badge-direct {
      background: #fff7ed;
      color: #c2410c;
      border: 1px solid #ffedd5;
    }
    .badge-indirect {
      background: #f5f3ff;
      color: #6d28d9;
      border: 1px solid #ede9fe;
    }
    .scene-box {
      width: 100%;
      height: 96px;
      background: #f8fafc;
      border-radius: 10px;
      display: flex;
      align-items: center;
      justify-content: space-around;
      padding: 0 8px;
      margin-bottom: 12px;
      position: relative;
      overflow: hidden;
    }
    .item-slot {
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      position: relative;
    }
    .emoji-main {
      font-size: 34px;
      line-height: 1;
    }
    .cross-mark {
      position: absolute;
      top: -4px;
      right: -6px;
      font-size: 16px;
      color: #ef4444;
      font-weight: 900;
      background: #ffffff;
      border-radius: 50%;
      width: 18px;
      height: 18px;
      display: flex;
      align-items: center;
      justify-content: center;
      box-shadow: 0 1px 3px rgba(0,0,0,0.15);
    }
    .relation-arrow {
      font-size: 20px;
      color: #94a3b8;
      font-weight: bold;
    }
    .impact-label {
      font-size: 15px;
      font-weight: 700;
      color: #1e2945;
      line-height: 1.3;
    }
    .hint-text {
      text-align: center;
      font-size: 13px;
      font-weight: 600;
      color: #64748b;
      margin-top: 10px;
    }
  </style>
</head>
<body>

  <div class="comparison-grid">
    
    <div class="impact-card active-direct" id="cardDirect" onclick="selectCard('direct')">
      <span class="badge badge-direct">Direct Impact</span>
      <div class="scene-box">
        <div class="item-slot">
          <span class="emoji-main">🥕</span>
          <span class="cross-mark">✕</span>
        </div>
        <span class="relation-arrow">➔</span>
        <div class="item-slot">
          <span class="emoji-main">🐰</span>
        </div>
      </div>
      <div class="impact-label">Herbivore loses food</div>
    </div>

    
    <div class="impact-card active-indirect" id="cardIndirect" onclick="selectCard('indirect')">
      <span class="badge badge-indirect">Indirect Impact</span>
      <div class="scene-box">
        <div class="item-slot">
          <span class="emoji-main">🐰</span>
          <span class="cross-mark">✕</span>
        </div>
        <span class="relation-arrow">➔</span>
        <div class="item-slot">
          <span class="emoji-main">🦊</span>
        </div>
      </div>
      <div class="impact-label">Carnivore loses prey</div>
    </div>
  </div>

  <div class="hint-text" id="hint">Tap a card to compare impacts</div>

  <script>
    function selectCard(type) {
      const cardDirect = document.getElementById('cardDirect');
      const cardIndirect = document.getElementById('cardIndirect');
      const hint = document.getElementById('hint');

      if (type === 'direct') {
        cardDirect.classList.add('active-direct');
        cardIndirect.classList.remove('active-indirect');
        hint.textContent = 'Direct: Immediate link (Producer → Herbivore)';
      } else {
        cardIndirect.classList.add('active-indirect');
        cardDirect.classList.remove('active-direct');
        hint.textContent = 'Indirect: Ripple effect (Producer → Herbivore → Carnivore)';
      }
    }
  </script>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }

    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
      background: #f8fafc;
      color: #1e293b;
      padding: 12px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: flex-start;
      min-height: auto;
      height: auto;
    }

    .container {
      width: 100%;
      max-width: 680px;
      display: flex;
      flex-direction: column;
      gap: 10px;
    }

    /* Header Bar */
    .header-bar {
      display: flex;
      align-items: center;
      justify-content: space-between;
      width: 100%;
    }

    .energy-title {
      font-size: 14px;
      font-weight: 700;
      text-transform: uppercase;
      letter-spacing: 0.6px;
      color: #0284c7;
      display: flex;
      align-items: center;
      gap: 8px;
    }

    .pulse-dot {
      width: 10px;
      height: 10px;
      border-radius: 50%;
      background: #0284c7;
      box-shadow: 0 0 8px #38bdf8;
      animation: glow 1.8s infinite ease-in-out;
    }

    @keyframes glow {
      0%, 100% { transform: scale(0.85); opacity: 0.6; }
      50% { transform: scale(1.2); opacity: 1; box-shadow: 0 0 12px #0284c7; }
    }

    .controls {
      display: flex;
      gap: 6px;
      align-items: center;
    }

    .btn-control {
      background: #ffffff;
      border: 1px solid #cbd5e1;
      border-radius: 6px;
      padding: 5px 10px;
      font-size: 12px;
      font-weight: 600;
      color: #334155;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      gap: 4px;
      transition: background-color 0.15s ease, border-color 0.15s ease;
    }

    .btn-control:active { background: #f1f5f9; }

    /* Desktop Chain Flow (Horizontal) */
    .chain-container {
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 4px;
      width: 100%;
      position: relative;
    }

    .chain-card {
      flex: 1;
      min-width: 0;
      background: #ffffff;
      border: 1.5px solid #e2e8f0;
      border-radius: 10px;
      padding: 8px 4px 8px;
      display: flex;
      flex-direction: column;
      align-items: center;
      text-align: center;
      position: relative;
      cursor: pointer;
      transition: box-shadow 0.25s ease, border-color 0.25s ease, background-color 0.25s ease;
    }

    .chain-card:hover {
      border-color: #94a3b8;
    }

    .chain-card.active {
      border-color: #0284c7;
      background: #f0f9ff;
      box-shadow: 0 0 0 2px #38bdf8, 0 4px 10px rgba(2, 132, 199, 0.18);
    }

    .icon-box {
      font-size: 26px;
      line-height: 1;
      margin-bottom: 4px;
      display: flex;
      align-items: center;
      justify-content: center;
      height: 36px;
      width: 36px;
      border-radius: 50%;
      transition: transform 0.2s ease;
    }

    .sun-glow {
      background: #fef08a;
      box-shadow: 0 0 10px #facc15;
    }

    .chain-card.active .sun-glow {
      box-shadow: 0 0 16px #eab308;
    }

    .name {
      font-size: 11px;
      font-weight: 700;
      color: #0f172a;
      margin-bottom: 4px;
      line-height: 1.2;
      word-break: break-word;
    }

    .badge {
      font-size: 9px;
      font-weight: 700;
      padding: 2px 4px;
      border-radius: 4px;
      line-height: 1.15;
      text-align: center;
      word-break: break-word;
      display: block;
    }

    .badge-yellow { background: #fef3c7; color: #b45309; }
    .badge-green  { background: #dcfce7; color: #15803d; }
    .badge-orange { background: #ffedd5; color: #c2410c; }
    .badge-purple { background: #f3e8ff; color: #7e22ce; }
    .badge-red    { background: #fee2e2; color: #b91c1c; }

    /* Flow Arrow Connector */
    .arrow-connector {
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      color: #94a3b8;
      font-size: 14px;
      font-weight: 900;
      flex-shrink: 0;
      padding: 0 1px;
      transition: color 0.3s ease, filter 0.3s ease;
    }

    .arrow-connector.active {
      color: #0284c7;
      filter: drop-shadow(0 0 4px #38bdf8);
    }

    /* Explanation Banner */
    .info-banner {
      background: #ffffff;
      border: 1px solid #e2e8f0;
      border-radius: 8px;
      padding: 8px 12px;
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 10px;
      font-size: 12px;
      color: #334155;
    }

    .info-step-title {
      font-weight: 700;
      color: #0284c7;
      white-space: nowrap;
    }

    .info-desc {
      flex: 1;
      font-size: 11.5px;
      line-height: 1.35;
      color: #475569;
    }

    /* Flow Progress Bar */
    .flow-bar-container {
      width: 100%;
      background: #ffffff;
      border: 1px solid #e2e8f0;
      border-radius: 8px;
      padding: 8px 12px;
      display: flex;
      align-items: center;
      gap: 10px;
    }

    .flow-label {
      font-size: 11px;
      font-weight: 700;
      color: #0284c7;
      white-space: nowrap;
      display: flex;
      align-items: center;
      gap: 4px;
    }

    .flow-arrow-track {
      flex: 1;
      position: relative;
      height: 6px;
      background: #e2e8f0;
      border-radius: 3px;
      overflow: hidden;
    }

    .flow-arrow-progress {
      position: absolute;
      left: 0;
      top: 0;
      height: 100%;
      width: 20%;
      background: linear-gradient(90deg, #38bdf8, #0284c7);
      border-radius: 3px;
      box-shadow: 0 0 6px #0284c7;
      transition: left 0.4s ease, width 0.4s ease;
    }

    /* Mobile Responsive Layout (< 520px) */
    @media (max-width: 520px) {
      body {
        padding: 8px 6px;
      }

      .container {
        gap: 8px;
      }

      /* Stack into a clean vertical connected list */
      .chain-container {
        flex-direction: column;
        gap: 4px;
      }

      .chain-card {
        width: 100%;
        flex-direction: row;
        text-align: left;
        padding: 6px 10px;
        gap: 10px;
        align-items: center;
        border-radius: 8px;
      }

      .icon-box {
        font-size: 22px;
        height: 32px;
        width: 32px;
        margin-bottom: 0;
        flex-shrink: 0;
      }

      .card-text-group {
        display: flex;
        align-items: center;
        justify-content: space-between;
        flex: 1;
        gap: 6px;
      }

      .name {
        font-size: 12px;
        margin-bottom: 0;
      }

      .badge {
        font-size: 10px;
        padding: 2px 6px;
      }

      .arrow-connector {
        font-size: 12px;
        padding: 1px 0;
      }

      /* Rotate connector arrow downward on mobile */
      .arrow-connector span {
        transform: rotate(90deg);
        display: inline-block;
      }

      .info-banner {
        flex-direction: column;
        align-items: flex-start;
        gap: 3px;
        padding: 6px 10px;
      }

      .info-step-title {
        font-size: 11px;
      }

      .info-desc {
        font-size: 11px;
      }
    }
  </style>
</head>
<body>

  <div class="container">
    
    <div class="header-bar">
      <div class="energy-title">
        <span class="pulse-dot"></span>
        Energy Flow Chain
      </div>
      <div class="controls">
        <button class="btn-control" id="playBtn" onclick="togglePlay()" aria-label="Pause or Play">
          <span id="playIcon">⏸</span> <span id="playText">Pause</span>
        </button>
      </div>
    </div>

    
    <div class="chain-container" id="chain">
      
      <div class="chain-card active" onclick="setStep(0)">
        <div class="icon-box sun-glow">☀️</div>
        <div class="card-text-group">
          <div class="name">Sun</div>
          <div class="badge badge-yellow">Light Energy</div>
        </div>
      </div>

      <div class="arrow-connector" id="arr0"><span>➔</span></div>

      
      <div class="chain-card" onclick="setStep(1)">
        <div class="icon-box">🌱</div>
        <div class="card-text-group">
          <div class="name">Grass</div>
          <div class="badge badge-green">Producer</div>
        </div>
      </div>

      <div class="arrow-connector" id="arr1"><span>➔</span></div>

      
      <div class="chain-card" onclick="setStep(2)">
        <div class="icon-box">🦗</div>
        <div class="card-text-group">
          <div class="name">Grasshopper</div>
          <div class="badge badge-orange">Herbivore</div>
        </div>
      </div>

      <div class="arrow-connector" id="arr2"><span>➔</span></div>

      
      <div class="chain-card" onclick="setStep(3)">
        <div class="icon-box">🐦</div>
        <div class="card-text-group">
          <div class="name">Meadowlark</div>
          <div class="badge badge-purple">Carnivore</div>
        </div>
      </div>

      <div class="arrow-connector" id="arr3"><span>➔</span></div>

      
      <div class="chain-card" onclick="setStep(4)">
        <div class="icon-box">🦅</div>
        <div class="card-text-group">
          <div class="name">Hawk</div>
          <div class="badge badge-red">Top Carnivore</div>
        </div>
      </div>
    </div>

    
    <div class="info-banner">
      <div class="info-step-title" id="stepTitle">Step 1: The Sun</div>
      <div class="info-desc" id="stepDesc">Primary radiant energy source that powers all life through photosynthesis.</div>
    </div>

    
    <div class="flow-bar-container">
      <div class="flow-label">Energy Flow ➔</div>
      <div class="flow-arrow-track">
        <div class="flow-arrow-progress" id="progress"></div>
      </div>
    </div>
  </div>

  <script>
    const stepsData = [
      {
        title: "1. The Sun (Energy Source)",
        desc: "Provides radiant solar energy that fuels the entire ecosystem through photosynthesis."
      },
      {
        title: "2. Grass (Producer)",
        desc: "Captures sunlight and converts it into chemical energy (glucose) via photosynthesis."
      },
      {
        title: "3. Grasshopper (Herbivore)",
        desc: "Primary consumer eats plants to gain energy for growth and daily movement."
      },
      {
        title: "4. Meadowlark (Carnivore)",
        desc: "Secondary consumer (insect-eater) feeds on herbivores to acquire stored energy."
      },
      {
        title: "5. Hawk (Top Carnivore)",
        desc: "Apex predator feeds on smaller carnivores at the top of this food chain."
      }
    ];

    let currentStep = 0;
    let isPlaying = true;
    let timer = null;
    const STEP_DURATION = 2200; // Comfortable 2.2s reading pace

    const cards = document.querySelectorAll('.chain-card');
    const arrows = [
      document.getElementById('arr0'),
      document.getElementById('arr1'),
      document.getElementById('arr2'),
      document.getElementById('arr3')
    ];
    const progressBar = document.getElementById('progress');
    const stepTitle = document.getElementById('stepTitle');
    const stepDesc = document.getElementById('stepDesc');
    const playIcon = document.getElementById('playIcon');
    const playText = document.getElementById('playText');

    function updateView() {
      cards.forEach((card, idx) => {
        if (idx === currentStep) {
          card.classList.add('active');
        } else {
          card.classList.remove('active');
        }
      });

      arrows.forEach((arr, idx) => {
        if (arr) {
          if (idx < currentStep) {
            arr.classList.add('active');
          } else {
            arr.classList.remove('active');
          }
        }
      });

      // Update progress bar
      progressBar.style.left = (currentStep * 20) + '%';
      progressBar.style.width = '20%';

      // Update educational text
      stepTitle.textContent = stepsData[currentStep].title;
      stepDesc.textContent = stepsData[currentStep].desc;
    }

    function nextStep() {
      currentStep = (currentStep + 1) % cards.length;
      updateView();
    }

    function setStep(idx) {
      currentStep = idx;
      updateView();
      if (isPlaying) {
        clearInterval(timer);
        timer = setInterval(nextStep, STEP_DURATION);
      }
    }

    function togglePlay() {
      isPlaying = !isPlaying;
      if (isPlaying) {
        playIcon.textContent = '⏸';
        playText.textContent = 'Pause';
        timer = setInterval(nextStep, STEP_DURATION);
      } else {
        playIcon.textContent = '▶';
        playText.textContent = 'Play';
        clearInterval(timer);
      }
    }

    // Initialize auto-play
    timer = setInterval(nextStep, STEP_DURATION);
    updateView();
  </script>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <title>Pond Food Chain</title>
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }

    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
      background: #f8fafc;
      color: #1e293b;
      padding: 12px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      min-height: 100%;
    }

    .main-wrap {
      width: 100%;
      max-width: 620px;
      display: flex;
      flex-direction: column;
      gap: 12px;
    }

    /* Chain Grid */
    .chain-container {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 8px;
      position: relative;
    }

    @media (max-width: 480px) {
      .chain-container {
        grid-template-columns: repeat(2, 1fr);
        gap: 10px;
      }
    }

    /* Card Item */
    .chain-card {
      background: #ffffff;
      border: 2px solid #e2e8f0;
      border-radius: 12px;
      padding: 10px 8px;
      display: flex;
      flex-direction: column;
      align-items: center;
      text-align: center;
      cursor: pointer;
      position: relative;
      transition: border-color 0.3s ease, box-shadow 0.3s ease, transform 0.2s ease;
      user-select: none;
    }

    .chain-card.active {
      border-color: #0284c7;
      box-shadow: 0 0 0 2px rgba(2, 132, 199, 0.25), 0 4px 12px rgba(2, 132, 199, 0.12);
      background: #f0f9ff;
    }

    .step-badge {
      position: absolute;
      top: 6px;
      left: 6px;
      font-size: 11px;
      font-weight: 700;
      color: #64748b;
      background: #f1f5f9;
      width: 20px;
      height: 20px;
      border-radius: 50%;
      display: flex;
      align-items: center;
      justify-content: center;
    }

    .chain-card.active .step-badge {
      background: #0284c7;
      color: #ffffff;
    }

    .icon-wrap {
      font-size: 32px;
      margin: 10px 0 6px;
      line-height: 1;
    }

    .title {
      font-size: 13px;
      font-weight: 700;
      color: #0f172a;
      margin-bottom: 2px;
      line-height: 1.2;
    }

    .role-tag {
      font-size: 11px;
      font-weight: 600;
      color: #0284c7;
      margin-bottom: 6px;
      line-height: 1.1;
    }

    /* Energy Bar */
    .energy-wrap {
      width: 100%;
      margin-top: auto;
      display: flex;
      flex-direction: column;
      gap: 3px;
    }

    .energy-label {
      font-size: 10px;
      font-weight: 700;
      color: #64748b;
      display: flex;
      justify-content: space-between;
      text-transform: uppercase;
      letter-spacing: 0.3px;
    }

    .energy-track {
      width: 100%;
      height: 8px;
      background: #e2e8f0;
      border-radius: 4px;
      overflow: hidden;
    }

    .energy-fill {
      height: 100%;
      background: linear-gradient(90deg, #f59e0b, #eab308);
      border-radius: 4px;
      transition: width 0.4s ease;
    }

    .card-1 .energy-fill { width: 100%; background: #16a34a; }
    .card-2 .energy-fill { width: 60%; background: #eab308; }
    .card-3 .energy-fill { width: 35%; background: #f97316; }
    .card-4 .energy-fill { width: 15%; background: #ef4444; }

    /* Flow Info Banner */
    .flow-info {
      background: #ffffff;
      border: 1px solid #e2e8f0;
      border-radius: 10px;
      padding: 10px 14px;
      display: flex;
      align-items: center;
      justify-content: space-between;
      min-height: 48px;
    }

    .info-text {
      font-size: 13px;
      font-weight: 600;
      color: #334155;
      display: flex;
      align-items: center;
      gap: 8px;
    }

    .info-text strong {
      color: #0284c7;
    }

    /* Controls */
    .controls {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
    }

    .btn {
      appearance: none;
      border: 1px solid #cbd5e1;
      background: #ffffff;
      color: #334155;
      padding: 6px 12px;
      border-radius: 6px;
      font-size: 12px;
      font-weight: 600;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      gap: 4px;
      transition: background 0.2s ease, border-color 0.2s ease;
    }

    .btn:active {
      background: #f1f5f9;
    }

    .step-dots {
      display: flex;
      gap: 6px;
      margin: 0 4px;
    }

    .dot {
      width: 10px;
      height: 10px;
      border-radius: 50%;
      background: #cbd5e1;
      border: none;
      cursor: pointer;
      padding: 0;
      transition: background 0.3s ease;
    }

    .dot.active {
      background: #0284c7;
    }
  </style>
</head>
<body>

  <div class="main-wrap">
    
    <div class="chain-container" id="chain">
      
      
      <div class="chain-card card-1 active" data-step="0">
        <span class="step-badge">1</span>
        <div class="icon-wrap">🌿</div>
        <div class="title">Algae</div>
        <div class="role-tag">Traps Sun Energy</div>
        <div class="energy-wrap">
          <div class="energy-label"><span>Energy</span><span>100%</span></div>
          <div class="energy-track"><div class="energy-fill"></div></div>
        </div>
      </div>

      
      <div class="chain-card card-2" data-step="1">
        <span class="step-badge">2</span>
        <div class="icon-wrap">🐌</div>
        <div class="title">Pond Snail</div>
        <div class="role-tag">Eats Algae</div>
        <div class="energy-wrap">
          <div class="energy-label"><span>Energy</span><span>60%</span></div>
          <div class="energy-track"><div class="energy-fill"></div></div>
        </div>
      </div>

      
      <div class="chain-card card-3" data-step="2">
        <span class="step-badge">3</span>
        <div class="icon-wrap">🐟</div>
        <div class="title">Perch Fish</div>
        <div class="role-tag">Eats Snail</div>
        <div class="energy-wrap">
          <div class="energy-label"><span>Energy</span><span>35%</span></div>
          <div class="energy-track"><div class="energy-fill"></div></div>
        </div>
      </div>

      
      <div class="chain-card card-4" data-step="3">
        <span class="step-badge">4</span>
        <div class="icon-wrap">🪶</div>
        <div class="title">Heron</div>
        <div class="role-tag">Eats Fish</div>
        <div class="energy-wrap">
          <div class="energy-label"><span>Energy</span><span>15%</span></div>
          <div class="energy-track"><div class="energy-fill"></div></div>
        </div>
      </div>

    </div>

    
    <div class="flow-info">
      <div class="info-text" id="infoText">
        <span>☀️</span>
        <span><strong>Sun ➔ Algae:</strong> Photosynthesis makes food energy</span>
      </div>
      <div class="info-arrow" style="font-weight: bold; color: #0284c7;">➔</div>
    </div>

    
    <div class="controls">
      <button class="btn" id="prevBtn" aria-label="Previous step">◀</button>
      <button class="btn" id="playBtn" aria-label="Play or pause">⏸ Pause</button>
      <div class="step-dots" id="dots">
        <button class="dot active" data-step="0" aria-label="Step 1"></button>
        <button class="dot" data-step="1" aria-label="Step 2"></button>
        <button class="dot" data-step="2" aria-label="Step 3"></button>
        <button class="dot" data-step="3" aria-label="Step 4"></button>
      </div>
      <button class="btn" id="nextBtn" aria-label="Next step">▶</button>
    </div>
  </div>

  <script>
    const descriptions = [
      "☀️ <strong>Sun ➔ Algae:</strong> Plant traps sunlight for energy",
      "🌿 <strong>Algae ➔ Snail:</strong> Snail eats algae for energy",
      "🐌 <strong>Snail ➔ Perch:</strong> Fish eats snail for energy",
      "🐟 <strong>Perch ➔ Heron:</strong> Heron eats fish for energy"
    ];

    const cards = document.querySelectorAll('.chain-card');
    const dots = document.querySelectorAll('.dot');
    const infoText = document.getElementById('infoText');
    const playBtn = document.getElementById('playBtn');
    const prevBtn = document.getElementById('prevBtn');
    const nextBtn = document.getElementById('nextBtn');

    let currentStep = 0;
    let isPlaying = true;
    let timer = null;

    function setStep(index) {
      currentStep = (index + cards.length) % cards.length;

      cards.forEach((card, idx) => {
        card.classList.toggle('active', idx === currentStep);
      });

      dots.forEach((dot, idx) => {
        dot.classList.toggle('active', idx === currentStep);
      });

      infoText.innerHTML = descriptions[currentStep];
    }

    function nextStep() {
      setStep(currentStep + 1);
    }

    function prevStep() {
      setStep(currentStep - 1);
    }

    function startAutoPlay() {
      if (timer) clearInterval(timer);
      timer = setInterval(nextStep, 3200);
      isPlaying = true;
      playBtn.textContent = '⏸ Pause';
    }

    function stopAutoPlay() {
      if (timer) clearInterval(timer);
      timer = null;
      isPlaying = false;
      playBtn.textContent = '▶ Play';
    }

    function togglePlay() {
      if (isPlaying) {
        stopAutoPlay();
      } else {
        nextStep();
        startAutoPlay();
      }
    }

    // Event listeners
    cards.forEach((card) => {
      card.addEventListener('click', () => {
        const step = parseInt(card.dataset.step, 10);
        setStep(step);
        stopAutoPlay();
      });
    });

    dots.forEach((dot) => {
      dot.addEventListener('click', () => {
        const step = parseInt(dot.dataset.step, 10);
        setStep(step);
        stopAutoPlay();
      });
    });

    playBtn.addEventListener('click', togglePlay);
    prevBtn.addEventListener('click', () => { prevStep(); stopAutoPlay(); });
    nextBtn.addEventListener('click', () => { nextStep(); stopAutoPlay(); });

    // Start playback
    startAutoPlay();
  </script>
</body>
</html>

What Is a Food Chain?

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <title>Food Chain Energy Flow</title>
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }
    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      color: #1e2945;
      background: transparent;
      padding: 8px 6px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      min-height: 100vh;
      box-sizing: border-box;
      user-select: none;
      overflow-x: hidden;
    }

    /* Header */
    .header {
      text-align: center;
      margin-bottom: 4px;
    }
    .header-tag {
      display: inline-flex;
      align-items: center;
      gap: 5px;
      font-size: 11px;
      font-weight: 700;
      letter-spacing: 0.4px;
      text-transform: uppercase;
      color: #b45309;
      background: #fef3c7;
      padding: 4px 12px;
      border-radius: 999px;
      border: 1px solid #fde68a;
    }

    /* Chain Layout */
    .chain-container {
      width: 100%;
      max-width: 600px;
      display: flex;
      align-items: stretch;
      justify-content: space-between;
      gap: 3px;
      margin: 6px 0;
      position: relative;
    }

    /* Organism Node */
    .node {
      flex: 1 1 0;
      min-width: 0;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: flex-start;
      text-align: center;
      padding: 8px 3px;
      border-radius: 12px;
      border: 1.5px solid rgba(0, 0, 0, 0.08);
      background: #ffffff;
      cursor: pointer;
      position: relative;
      transition: border-color 0.3s ease, background-color 0.3s ease, box-shadow 0.3s ease;
    }

    .node:active {
      opacity: 0.92;
    }

    .node.active {
      border-color: #f59e0b;
      box-shadow: 0 0 0 3px rgba(245, 158, 11, 0.25), 0 3px 10px rgba(245, 158, 11, 0.15);
    }

    .node.lit {
      border-color: #f59e0b;
      background: #fffbeb;
      box-shadow: 0 0 0 3px rgba(245, 158, 11, 0.35);
    }

    /* Node color accents */
    .node-1 { background: #f0fdf4; border-color: #bbf7d0; }
    .node-2 { background: #fefce8; border-color: #fef08a; }
    .node-3 { background: #fff7ed; border-color: #fed7aa; }
    .node-4 { background: #f8fafc; border-color: #cbd5e1; }

    .node-icon-wrap {
      width: 42px;
      height: 42px;
      border-radius: 50%;
      display: flex;
      align-items: center;
      justify-content: center;
      margin-bottom: 4px;
      background: #ffffff;
      box-shadow: 0 1px 3px rgba(0, 0, 0, 0.08);
      flex-shrink: 0;
    }

    .node-icon-svg {
      width: 26px;
      height: 26px;
      display: block;
    }

    .node-title {
      font-size: 11px;
      font-weight: 700;
      color: #0f172a;
      line-height: 1.15;
      margin-bottom: 3px;
      white-space: normal;
      word-break: normal;
      overflow-wrap: break-word;
      hyphens: auto;
      width: 100%;
      min-height: 25px;
      display: flex;
      align-items: center;
      justify-content: center;
    }

    .node-role {
      font-size: 9.5px;
      font-weight: 600;
      color: #64748b;
      line-height: 1.1;
      white-space: normal;
      word-break: break-word;
    }

    /* Connecting Arrows */
    .arrow-connector {
      flex: 0 0 auto;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      width: 20px;
      position: relative;
      align-self: center;
      padding: 0 1px;
    }

    .arrow-svg {
      width: 100%;
      max-width: 22px;
      height: 14px;
      overflow: visible;
    }

    .arrow-label {
      font-size: 7.5px;
      font-weight: 700;
      color: #d97706;
      text-transform: uppercase;
      letter-spacing: -0.2px;
      line-height: 1;
      margin-top: 2px;
      white-space: nowrap;
      text-align: center;
    }

    .arrow-energy-pulse {
      fill: #f59e0b;
      opacity: 0.9;
      animation: pulseTravel 1.6s infinite ease-in-out;
    }

    .arrow-connector:nth-of-type(2) .arrow-energy-pulse {
      animation-delay: 0s;
    }
    .arrow-connector:nth-of-type(4) .arrow-energy-pulse {
      animation-delay: 0.4s;
    }
    .arrow-connector:nth-of-type(6) .arrow-energy-pulse {
      animation-delay: 0.8s;
    }

    @keyframes pulseTravel {
      0% { transform: translateX(-1px); opacity: 0.2; }
      40% { opacity: 1; }
      80% { opacity: 1; }
      100% { transform: translateX(15px); opacity: 0.2; }
    }

    /* Dynamic Info Bar */
    .info-bar {
      width: 100%;
      max-width: 540px;
      background: #f8fafc;
      border: 1.5px solid #e2e8f0;
      border-radius: 12px;
      padding: 8px 12px;
      margin: 6px 0;
      display: flex;
      align-items: center;
      gap: 10px;
      min-height: 48px;
      transition: background-color 0.3s ease, border-color 0.3s ease;
    }

    .info-badge {
      font-size: 10px;
      font-weight: 800;
      padding: 4px 8px;
      border-radius: 6px;
      background: #f59e0b;
      color: #ffffff;
      white-space: nowrap;
      text-transform: uppercase;
      letter-spacing: 0.3px;
      flex-shrink: 0;
      transition: background-color 0.3s ease;
    }

    .info-text {
      font-size: 12.5px;
      line-height: 1.35;
      font-weight: 500;
      color: #334155;
      flex: 1;
    }
    .info-text strong {
      color: #0f172a;
      font-weight: 700;
    }

    /* Controls Bar */
    .controls {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      width: 100%;
      margin-top: 2px;
    }

    .btn {
      appearance: none;
      border: 1px solid #cbd5e1;
      background: #ffffff;
      color: #1e2945;
      font-size: 11.5px;
      font-weight: 600;
      padding: 5px 12px;
      border-radius: 999px;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      gap: 5px;
      transition: background-color 0.2s, border-color 0.2s;
    }

    .btn:active {
      opacity: 0.9;
    }

    .btn-primary {
      background: #f59e0b;
      color: #ffffff;
      border-color: #d97706;
    }

    .btn-primary:active {
      background: #d97706;
    }

    .step-dots {
      display: flex;
      gap: 6px;
      margin-left: 2px;
      align-items: center;
    }

    .dot {
      width: 8px;
      height: 8px;
      border-radius: 50%;
      background: #cbd5e1;
      cursor: pointer;
      transition: background-color 0.3s ease, transform 0.2s ease;
    }

    .dot.active {
      background: #f59e0b;
      transform: scale(1.15);
    }

    /* Responsive adjustments for narrow screens (320px - 400px) */
    @media (max-width: 400px) {
      .chain-container {
        gap: 1px;
      }
      .node {
        padding: 6px 2px;
        border-radius: 9px;
      }
      .node-icon-wrap {
        width: 34px;
        height: 34px;
        margin-bottom: 2px;
      }
      .node-icon-svg {
        width: 20px;
        height: 20px;
      }
      .node-title {
        font-size: 10px;
        line-height: 1.1;
        min-height: 22px;
        margin-bottom: 1px;
      }
      .node-role {
        font-size: 8px;
        line-height: 1;
      }
      .arrow-connector {
        width: 14px;
        padding: 0;
      }
      .arrow-svg {
        max-width: 14px;
        height: 11px;
      }
      .arrow-label {
        display: none; /* Hide squeezed text label on narrow viewports to avoid overlapping card borders */
      }
      .info-bar {
        padding: 7px 9px;
        min-height: 44px;
        gap: 6px;
      }
      .info-badge {
        font-size: 9px;
        padding: 3px 6px;
      }
      .info-text {
        font-size: 11.5px;
        line-height: 1.25;
      }
      .btn {
        font-size: 10.5px;
        padding: 4px 10px;
      }
    }
  </style>
</head>
<body>

  
  <div class="header">
    <span class="header-tag">
      <svg width="12" height="12" viewBox="0 0 24 24" fill="#d97706">
        <path d="M13 2L3 14h9l-1 8 10-12h-9l1-8z"/>
      </svg>
      Energy Flow in a Food Chain
    </span>
  </div>

  
  <div class="chain-container" id="chain">
    
    
    <div class="node node-1 active lit" data-index="0">
      <div class="node-icon-wrap">
        
        <svg class="node-icon-svg" viewBox="0 0 32 32">
          <circle cx="8" cy="8" r="4.5" fill="#f59e0b"/>
          <path d="M8 1.5v2M8 12.5v2M1.5 8h2M12.5 8h2M3.4 3.4l1.4 1.4M11.2 11.2l1.4 1.4M3.4 12.6l1.4-1.4M11.2 4.8l1.4-1.4" stroke="#f59e0b" stroke-width="1.2" stroke-linecap="round"/>
          <path d="M7 28c1-6 4-10 8-12-1 4-1 8-2 12" fill="#22c55e"/>
          <path d="M14 28c2-7 6-12 12-14-2 5-3 10-4 14" fill="#16a34a"/>
          <path d="M20 28c1-5 4-8 8-9-1 4-1 7-2 9" fill="#4ade80"/>
        </svg>
      </div>
      <div class="node-title">Sun &amp; Grass</div>
      <div class="node-role">Producer</div>
    </div>

    
    <div class="arrow-connector">
      <svg class="arrow-svg" viewBox="0 0 20 12">
        <path d="M1 6 L15 6 M11 2 L16 6 L11 10" fill="none" stroke="#f59e0b" stroke-width="2.2" stroke-linecap="round" stroke-linejoin="round"/>
        <circle class="arrow-energy-pulse" cx="2" cy="6" r="2"/>
      </svg>
      <span class="arrow-label">Energy</span>
    </div>

    
    <div class="node node-2" data-index="1">
      <div class="node-icon-wrap">
        
        <svg class="node-icon-svg" viewBox="0 0 32 32">
          <ellipse cx="14" cy="16" rx="9" ry="4.5" transform="rotate(-10 14 16)" fill="#84cc16"/>
          <circle cx="23" cy="13" r="3.5" fill="#65a30d"/>
          <circle cx="24" cy="12" r="1" fill="#1e293b"/>
          
          <path d="M24 10c2-4 5-6 7-6" fill="none" stroke="#4d7c0f" stroke-width="1.2" stroke-linecap="round"/>
          
          <path d="M10 17l-5-7 4 14" fill="none" stroke="#4d7c0f" stroke-width="1.8" stroke-linecap="round" stroke-linejoin="round"/>
          <path d="M14 18l2 6" fill="none" stroke="#4d7c0f" stroke-width="1.4" stroke-linecap="round"/>
        </svg>
      </div>
      <div class="node-title">Grasshopper</div>
      <div class="node-role">Herbivore</div>
    </div>

    
    <div class="arrow-connector">
      <svg class="arrow-svg" viewBox="0 0 20 12">
        <path d="M1 6 L15 6 M11 2 L16 6 L11 10" fill="none" stroke="#f59e0b" stroke-width="2.2" stroke-linecap="round" stroke-linejoin="round"/>
        <circle class="arrow-energy-pulse" cx="2" cy="6" r="2"/>
      </svg>
      <span class="arrow-label">Energy</span>
    </div>

    
    <div class="node node-3" data-index="2">
      <div class="node-icon-wrap">
        
        <svg class="node-icon-svg" viewBox="0 0 32 32">
          <ellipse cx="14" cy="18" rx="8" ry="6" fill="#64748b"/>
          <path d="M12 16c3 0 7 2 7 6a6 6 0 01-8 2c-1-3 0-6 1-8z" fill="#ea580c"/>
          <circle cx="20" cy="13" r="4.5" fill="#475569"/>
          <circle cx="21.5" cy="12" r="1" fill="#ffffff"/>
          <circle cx="21.8" cy="12" r="0.6" fill="#0f172a"/>
          
          <path d="M24 13l5 1.5-5 2z" fill="#f59e0b"/>
          
          <path d="M7 19l-5 3 4-6z" fill="#334155"/>
          
          <path d="M13 24v4M16 24v4" stroke="#475569" stroke-width="1.2" stroke-linecap="round"/>
        </svg>
      </div>
      <div class="node-title">Robin</div>
      <div class="node-role">Carnivore</div>
    </div>

    
    <div class="arrow-connector">
      <svg class="arrow-svg" viewBox="0 0 20 12">
        <path d="M1 6 L15 6 M11 2 L16 6 L11 10" fill="none" stroke="#f59e0b" stroke-width="2.2" stroke-linecap="round" stroke-linejoin="round"/>
        <circle class="arrow-energy-pulse" cx="2" cy="6" r="2"/>
      </svg>
      <span class="arrow-label">Energy</span>
    </div>

    
    <div class="node node-4" data-index="3">
      <div class="node-icon-wrap">
        
        <svg class="node-icon-svg" viewBox="0 0 32 32">
          <path d="M16 12c-4-6-10-8-14-7 4 4 6 9 8 13" fill="#78350f" opacity="0.9"/>
          <path d="M16 12c3-6 9-8 13-7-4 4-6 9-8 13" fill="#92400e"/>
          <ellipse cx="16" cy="17" rx="4" ry="7" fill="#b45309"/>
          <circle cx="16" cy="10" r="3.5" fill="#d97706"/>
          
          <path d="M15 11c0 2-2 3-3 2" fill="none" stroke="#f59e0b" stroke-width="1.6" stroke-linecap="round"/>
          <circle cx="17" cy="9.5" r="0.8" fill="#0f172a"/>
          
          <path d="M14 24l2 5 2-5z" fill="#78350f"/>
        </svg>
      </div>
      <div class="node-title">Hawk</div>
      <div class="node-role">Top Predator</div>
    </div>

  </div>

  
  <div class="info-bar" id="infoBar">
    <div class="info-badge" id="infoBadge">Producer</div>
    <div class="info-text" id="infoText">
      <strong>Sun &amp; Grass:</strong> Absorbs sunlight to make food through photosynthesis.
    </div>
  </div>

  
  <div class="controls">
    <button class="btn btn-primary" id="playBtn" type="button">
      <span id="playIcon">⏸</span>
      <span id="playText">Energy Flow</span>
    </button>
    <button class="btn" id="nextBtn" type="button">Next ➔</button>
    <div class="step-dots" id="dotsGroup">
      <div class="dot active" data-index="0" title="Step 1: Producer"></div>
      <div class="dot" data-index="1" title="Step 2: Primary Consumer"></div>
      <div class="dot" data-index="2" title="Step 3: Secondary Consumer"></div>
      <div class="dot" data-index="3" title="Step 4: Apex Predator"></div>
    </div>
  </div>

  <script>
    const data = [
      {
        badge: "Producer",
        badgeColor: "#16a34a",
        text: "<strong>Sun & Grass:</strong> Captures solar energy to produce food through photosynthesis."
      },
      {
        badge: "Primary Consumer",
        badgeColor: "#65a30d",
        text: "<strong>Grasshopper:</strong> Herbivore that eats grass to gain stored plant energy."
      },
      {
        badge: "Secondary Consumer",
        badgeColor: "#ea580c",
        text: "<strong>Robin:</strong> Carnivore that eats the grasshopper for energy."
      },
      {
        badge: "Apex Predator",
        badgeColor: "#b45309",
        text: "<strong>Hawk:</strong> Top predator that hunts the robin; sits at the top of this chain."
      }
    ];

    let currentIndex = 0;
    let timer = null;
    let isPlaying = true;

    const nodes = document.querySelectorAll('.node');
    const dots = document.querySelectorAll('.dot');
    const infoBadge = document.getElementById('infoBadge');
    const infoText = document.getElementById('infoText');
    const playBtn = document.getElementById('playBtn');
    const playIcon = document.getElementById('playIcon');
    const nextBtn = document.getElementById('nextBtn');

    function updateStep(index) {
      currentIndex = index;
      
      nodes.forEach((node, idx) => {
        if (idx === index) {
          node.classList.add('active', 'lit');
        } else {
          node.classList.remove('active', 'lit');
        }
      });

      dots.forEach((dot, idx) => {
        dot.classList.toggle('active', idx === index);
      });

      infoBadge.textContent = data[index].badge;
      infoBadge.style.backgroundColor = data[index].badgeColor;
      infoText.innerHTML = data[index].text;
    }

    function nextStep() {
      const next = (currentIndex + 1) % data.length;
      updateStep(next);
    }

    function startAutoPlay() {
      if (timer) clearInterval(timer);
      // Ensure node displays for at least 2600ms with gentle 300ms CSS transitions
      timer = setInterval(nextStep, 2800);
      isPlaying = true;
      playIcon.textContent = '⏸';
    }

    function pauseAutoPlay() {
      if (timer) clearInterval(timer);
      isPlaying = false;
      playIcon.textContent = '▶';
    }

    // Node tap
    nodes.forEach((node) => {
      node.addEventListener('click', () => {
        pauseAutoPlay();
        const idx = parseInt(node.getAttribute('data-index'), 10);
        updateStep(idx);
      });
    });

    // Dot tap
    dots.forEach((dot) => {
      dot.addEventListener('click', () => {
        pauseAutoPlay();
        const idx = parseInt(dot.getAttribute('data-index'), 10);
        updateStep(idx);
      });
    });

    // Play/Pause toggle
    playBtn.addEventListener('click', () => {
      if (isPlaying) {
        pauseAutoPlay();
      } else {
        startAutoPlay();
      }
    });

    // Manual Next
    nextBtn.addEventListener('click', () => {
      pauseAutoPlay();
      nextStep();
    });

    // Initialize
    updateStep(0);
    startAutoPlay();
  </script>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }

    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      background: #ffffff;
      color: #1e293b;
      padding: 12px;
      display: flex;
      flex-direction: column;
      gap: 12px;
      justify-content: center;
      min-height: 100%;
    }

    /* Section Containers */
    .panel {
      border-radius: 12px;
      padding: 12px 14px;
      position: relative;
    }

    .correct-panel {
      background: #f0fdf4;
      border: 1.5px solid #86efac;
    }

    .incorrect-panel {
      background: #fef2f2;
      border: 1.5px dashed #fca5a5;
    }

    /* Header Badges */
    .badge {
      display: inline-flex;
      align-items: center;
      gap: 4px;
      font-size: 13px;
      font-weight: 700;
      padding: 3px 8px;
      border-radius: 6px;
      margin-bottom: 8px;
      text-transform: uppercase;
      letter-spacing: 0.5px;
    }

    .badge-correct {
      background: #dcfce7;
      color: #15803d;
    }

    .badge-incorrect {
      background: #fee2e2;
      color: #b91c1c;
    }

    /* Row Layout */
    .chain-row {
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 8px;
    }

    /* Organism Cards */
    .organism-card {
      background: #ffffff;
      border: 1px solid #e2e8f0;
      border-radius: 10px;
      padding: 8px;
      text-align: center;
      flex: 1;
      max-width: 120px;
      box-shadow: 0 1px 3px rgba(0, 0, 0, 0.04);
    }

    .organism-icon {
      font-size: 32px;
      line-height: 1.1;
      display: block;
      margin-bottom: 2px;
    }

    .organism-name {
      font-size: 14px;
      font-weight: 700;
      color: #0f172a;
    }

    .organism-role {
      font-size: 11px;
      font-weight: 600;
      color: #64748b;
      margin-top: 1px;
    }

    /* Arrow Connectors */
    .arrow-container {
      flex: 1.4;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      position: relative;
      padding: 0 4px;
    }

    .arrow-label {
      font-size: 12px;
      font-weight: 700;
      color: #166534;
      background: #dcfce7;
      padding: 2px 8px;
      border-radius: 12px;
      margin-bottom: 4px;
      white-space: nowrap;
    }

    .arrow-svg {
      width: 100%;
      height: 28px;
      overflow: visible;
    }

    /* Continuous Energy Flow Animation */
    .energy-stream {
      stroke-dasharray: 8 8;
      animation: energyFlow 1.2s linear infinite;
    }

    @keyframes energyFlow {
      from {
        stroke-dashoffset: 32;
      }
      to {
        stroke-dashoffset: 0;
      }
    }

    /* Incorrect Arrow Overlay */
    .cross-mark {
      position: absolute;
      font-size: 26px;
      color: #dc2626;
      font-weight: 900;
      line-height: 1;
      text-shadow: 0 0 4px #ffffff;
    }

    .incorrect-caption {
      font-size: 12px;
      font-weight: 600;
      color: #991b1b;
      text-align: center;
      margin-top: 6px;
    }

    /* Compact Mobile Optimization */
    @media (max-width: 400px) {
      body {
        padding: 8px;
        gap: 8px;
      }
      .panel {
        padding: 8px 10px;
      }
      .organism-icon {
        font-size: 26px;
      }
      .organism-name {
        font-size: 12px;
      }
      .organism-role {
        font-size: 10px;
      }
      .arrow-label {
        font-size: 10px;
      }
    }
  </style>
</head>
<body>

  
  <div class="panel correct-panel">
    <div class="badge badge-correct">✓ Correct Direction</div>
    
    <div class="chain-row">
      <div class="organism-card">
        <span class="organism-icon">🍓</span>
        <div class="organism-name">Plant</div>
        <div class="organism-role">Gives Energy</div>
      </div>

      <div class="arrow-container">
        <span class="arrow-label">⚡ Energy Flows ➔</span>
        <svg class="arrow-svg" viewBox="0 0 120 24">
          <defs>
            <marker id="arrow-head-green" markerWidth="6" markerHeight="6" refX="5" refY="3" orient="auto">
              <polygon points="0 0, 6 3, 0 6" fill="#16a34a" />
            </marker>
          </defs>
          
          <line x1="4" y1="12" x2="112" y2="12" stroke="#bbf7d0" stroke-width="6" stroke-linecap="round" />
          
          <line class="energy-stream" x1="4" y1="12" x2="110" y2="12" stroke="#16a34a" stroke-width="4" stroke-linecap="round" marker-end="url(#arrow-head-green)" />
        </svg>
      </div>

      <div class="organism-card">
        <span class="organism-icon">🐇</span>
        <div class="organism-name">Rabbit</div>
        <div class="organism-role">Gets Energy</div>
      </div>
    </div>
  </div>

  
  <div class="panel incorrect-panel">
    <div class="badge badge-incorrect">✗ Common Mistake</div>

    <div class="chain-row">
      <div class="organism-card">
        <span class="organism-icon">🐇</span>
        <div class="organism-name">Rabbit</div>
      </div>

      <div class="arrow-container">
        <div class="cross-mark">✕</div>
        <svg class="arrow-svg" viewBox="0 0 120 24">
          <defs>
            <marker id="arrow-head-red" markerWidth="6" markerHeight="6" refX="5" refY="3" orient="auto">
              <polygon points="0 0, 6 3, 0 6" fill="#ef4444" />
            </marker>
          </defs>
          <line x1="4" y1="12" x2="110" y2="12" stroke="#fca5a5" stroke-width="4" stroke-linecap="round" marker-end="url(#arrow-head-red)" />
        </svg>
      </div>

      <div class="organism-card">
        <span class="organism-icon">🍓</span>
        <div class="organism-name">Plant</div>
      </div>
    </div>

    <div class="incorrect-caption">Arrows show energy flow, NOT "who eats what".</div>
  </div>

</body>
</html>

science.ks2.y2.t2.s3

Aligned learning resources

Related diagrams